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    • 专利摘要:
    The present invention relates to materials for generating mechanical coupling in elastomeric compositions, usable in particular for the manufacture of tire treads. In particular, it relates to a tread comprising a high and low modulus stiffness layer stack.
    公开号:FR3045495A1
    申请号:FR1563041
    申请日:2015-12-22
    公开日:2017-06-23
    发明作者:Da Silva Jose-Carlos Araujo；Masayuki Maesaka；Philippe Mansuy
    申请人:Michelin Recherche et Technique SA Switzerland ；Compagnie Generale des Etablissements Michelin SCA；Michelin Recherche et Technique SA France；
    IPC主号:
    专利说明:

    Technical area
    The present invention relates to materials for generating mechanical coupling in elastomeric compositions, usable in particular for the manufacture of tire treads.
    STATE OF THE ART Improving the wear resistance of tires is a very important problem, particularly because of the cost of the tires. This problem concerns all types of tires, but is even more important for tires for heavy goods vehicles and civil engineering vehicles because of the economic impact of immobilizing vehicles when replacing worn tires.
    Particularly, in the field of civil engineering, and in particular the mining sector, tires are used mainly on ore or coal extraction sites, as well as in quarries. The use consists, in a simplified way, in: - A cycle going in load, generally in rise for the ore and the coal, generally in descent for the quarries, to transport the ore or the sterile material towards the unloading zones (« crusher "for ore," dumping zones "for sterile material); - An empty return cycle, usually downhill for mining use, usually uphill for quarry use, to return to the loading areas.
    The tires fitted to the mining dumpers concerned are, as a rule, mounted on the front axle of the vehicle during the first third of their life, and then swapped in twinned on the rear axle for the two thirds of life remaining. The engine torque is transmitted via the rear axle, the braking torque is also almost exclusively transmitted via the rear axle using the engine brake (thermal or electrical in the case of such a transmission).
    From the point of view of a mine manager, the transportation of ore and sterile material accounts for a significant portion of the operational costs of the mine, and the share of tires in this contribution is significant. Limiting the speed of wear is therefore a major axis of reduction of operating costs. From the point of view of the tire manufacturer, developing technical solutions to reduce the speed of wear is therefore an important strategic element.
    The mining tires of the rear axle of the rigid dumpers are subjected to significant efforts (passage of engine torque and braking) because the slopes of the tracks to leave the open pit mines ("pit" in English) are generally of the order of 8.5 to 10%. This slope value optimizes vehicle productivity with the current available power. These stresses result in a relatively fast wear of the tires. It is therefore a question of proposing a technical solution making it possible to improve the tire wear performance of this axle, both under engine torque under load and under vacuum braking torque.
    Many solutions have been sought to increase the wear resistance so as to prolong their life as much as possible and thus reduce operating costs.
    In the field of tires for civil engineering vehicles, it is known to use in treads of off-road vehicles, natural rubber, a reinforcing filler of the carbon black type and the additives usually used for these tires. The improvement in the wear resistance of this type of tire is generally achieved by optimizing the nature of its constituents or its sculptures. For example, to improve the wear resistance of off-road tires, WO 2013/041400 proposes to incorporate a certain amount of high vinyl polybutadiene into an isoprenic matrix of a tread composition.
    In the field of tires for vehicles traveling on bituminous surfaces such as passenger vehicles or most heavy goods vehicles, a solution to improve the wear resistance has been proposed in US Pat. No. 8,272,412 by integrating, into an elastomeric composition. for tread, glass fibers oriented at 45 degrees to the direction of rolling in the circumferential plane.
    However, it is still necessary to provide improved solutions to improve the wear resistance of tires in general, and particularly for tires of heavy goods vehicles or civil engineering vehicles.
    Presentation of the invention
    Accordingly, the present invention relates to a novel tire formulation for significantly improving their wear resistance.
    It particularly relates to a tread comprising at least one sculpture consisting of a plurality of parallel layers and adjacent to each other, the layers being oriented in the sculpture parallel to a plane which is (i) perpendicular to the equatorial plane and (ii) ) oriented at an angle expressed in degrees to the radial plane, the angle a being defined by the formula a = 45 +/- x, where x is within a range of 10 to 30; the plurality of layers comprising layers consisting of a composition with a low stiffness modulus whose expansion modulus at 5% of deformation is in a range from 2 to 8 MPa and layers consisting of a composition with a high modulus of rigidity including the 5% strain extension module in a range from 30 MPa to 50 GPa.
    The tread according to the invention can be either in the green state (before crosslinking or vulcanization), or in the fired state (after crosslinking or vulcanization). It can be in the form of a semi-finished product that can be used in a tire or on a retreaded carcass, or can be already disposed on a tire or a tire casing. Definitions
    By the term "part by weight per hundred parts by weight of elastomer" (or phr) is meant for the purposes of the present invention, the part, by weight per hundred parts by weight of elastomer or rubber.
    In the present, unless expressly indicated otherwise, all the percentages (%) indicated are percentages (%) by mass. On the other hand, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the term "from a to b" means the range from a to b (i.e., including the strict limits a and b). In the present invention, when a range of values is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also designated and preferentially.
    As used herein, "composition based on" is understood to mean a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents being capable of or intended to react between they, at least in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization. By way of example, a composition based on an elastomer and sulfur matrix comprises the elastomeric matrix and the sulfur before firing, whereas after firing the sulfur is no longer detectable because the latter has reacted with the elastomeric matrix while forming disulfide bridges.
    Herewith the term "predominantly" includes more than 50%. For example, it may be more than 60%, 70%, 80%, 90% or even 100%.
    At a given point of a tire, the circumferential direction, also called the longitudinal direction, is the tangent direction of a circle centered on the axis of rotation of the tire. It is parallel to the rolling direction of the tire. The axis of rotation of the tire is the axis around which it rotates under normal use. At a given point of a tire, the transverse direction, also called the lateral direction, is parallel to the axis of rotation of the tire. At a given point of a tire, the radial direction is a direction intersecting the axis of rotation of the tire and perpendicular to it. X is a direction parallel to the circumferential direction, Y is a direction parallel to the transverse direction, and Z is a direction parallel to the radial direction. The XYZ directions form an orthogonal reference (Figure 1).
    "Fx" is understood to mean the horizontal component of the forces of the ground on the tire in the running direction of the tire. We speak of motor torque when a positive force Fx is applied and braking torque when a negative force Fx is applied. By "Fy" is meant the horizontal component of the forces of the ground on the tire in the transverse direction of the tire. "Fz" means the vertical component.
    The term "coupling ratio" is the ratio of the horizontal component Fx of the forces of the ground on the tire (or of the ground on the specimen) to the vertical component Fz of the forces of the ground on the tire (or of the ground on the tire). test).
    A radial plane "YZ", also called meridian plane, is a plane which contains the axis of rotation of the tire. A circumferential plane "XZ" is a plane perpendicular to the axis of rotation of the tire. The circumferential mid-plane, also called the equatorial plane, is a plane perpendicular to the axis of rotation of the tire and divides the tire into two halves.
    In the present, the term "sculpture" means a more or less complex system of relief elements separated from each other by cutouts. The relief elements of a sculpture can be either ribs or blocks.
    By "rib" ("rib" in English) is meant a raised element formed on a tread and extending substantially in the circumferential direction, this element being delimited either by two cutouts or by a cutout and an edge of the tread. A rib comprises two side walls and a contact face, the latter being intended to come into contact with the roadway during driving. This element extends in the circumferential direction and goes around the tire (legend (2) of Figure 1).
    By "block" ("tread block" in English) is meant a raised element formed on a tread, this element being delimited by one or more rectilinear, curved or circular cutouts, and possibly by an edge of the tread block. rolling. A block also comprising a contact face, the latter being intended to come into contact with the roadway during taxiing (legend (3) of Figure 1).
    The cutouts may be either grooves or incisions according to their thickness, that is to say the distance between the walls of material that delimit and their operation during driving. The thickness of a groove is typically at least 1 mm, while the thickness of an incision is typically at most equal to 1 mm. When rolling the tire, the material walls of a groove do not come into contact with each other, while the material walls of an incision come into contact at least partly with each other. 'other.
    In the present, a "cut out" ("eut out" in English) designates a groove and corresponds to the space delimited by material walls facing each other and distant from each other by a non-zero distance, preferably greater than 1 mm, for example greater than 2, 3, 4 or 5 mm (legends (4) and (5) of Figure 1).
    In the context of the invention, the carbonaceous products mentioned in the description may be of fossil origin or biobased. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass.
    Composition with low modulus of rigidity
    According to the invention, the tread consists of a plurality of layers comprising layers consisting of a composition with a low modulus of rigidity. The term "low stiffness modulus composition" is intended to mean a composition whose extension modulus at 5% of deformation is within a range of from 2 to 8 MPa. Preferably, the 5% deformation modulus of the low rigidity modulus composition is within a range of 3 to 6 MPa. Those skilled in the art can measure the rigidity of which the extension module at 5% deformation according to a method based on the NF ISO 37 standard of December 2005 on a dumbbell type 2 specimen and measure the modulus of elasticity at 5%. deformation at 23 ° C.
    The low rigidity modulus composition may advantageously be an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler and at least one crosslinking system.
    Elastomer matrix of the composition with a low modulus of ripidity
    According to the invention, any elastomeric matrix known to those skilled in the art for the manufacture of tread may be used in the low modulus stiffness composition of the tread pattern according to the invention.
    For example, the elastomeric matrix may comprise a diene elastomer, preferably an elastomer chosen from isoprenic elastomers, butadiene and styrene copolymers, polybutadienes and their mixtures.
    By "diene" elastomer, it is to be understood in a known manner (one or more elastomers) are understood to come from at least a part (ie, a homopolymer or a copolymer) of monomers dienes (monomers carrying two carbon-carbon double bonds, conjugated or not).
    These diene elastomers are well known to those skilled in the art and can be classified into two categories: "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); Thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "essentially saturated" diene elastomers ( low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
    The term "diene elastomer" that may be used in the compositions according to the invention is more particularly understood to mean: a) any homopolymer of a conjugated diene monomer, especially any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 atoms of carbon; b) any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms; c) a ternary copolymer obtained by copolymerization of ethylene, an α-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having from 6 to 12 carbon atoms, for example elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene; d) a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, in particular chlorinated or brominated, of this type of copolymer.
    Although it applies to any type of diene elastomer, the person skilled in the tire art will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b). ) above. In the case of copolymers of type (b), these contain from 20 to 99% by weight of diene units and from 1 to 80% by weight of vinylaromatic units. As conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Suitable vinyl aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
    By "isoprene elastomer" is meant in known manner a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), different isoprene copolymers and mixtures of these elastomers. Among the isoprene copolymers, mention will in particular be made of copolymers of isobutene-isoprene (butyl rubber - IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene (SBIR). This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene, preferably natural rubber. For example, the synthetic polyisoprene may be a polyisoprene having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%.
    The elastomers used in the context of the present invention may for example be block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred and / or functionalized with a coupling agent and / or starring and / or functionalization. The isoprene elastomer may be chosen from the group comprising natural rubber, synthetic polyisoprene and their mixture. Preferably, the isoprene elastomer is natural rubber.
    For the purposes of the present invention, the term "copolymer of butadiene units and styrenic units" refers to any copolymer obtained by copolymerization of one or more butadiene (s) with one or more styrenic compounds. Suitable styrene compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene. These elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and amounts of modifying and / or randomizing agent used. The elastomers can be, for example, block, random, sequenced, microsequenced, and be prepared in dispersion or in solution.
    The butadiene and styrene copolymer may be, for example, butadiene-styrene copolymer (SBR). It may be, for example, an emulsion-prepared SBR ("ESBR") or a solution-prepared SBR ("SSBR"). The levels of vinyl (-1.2), trans-1,4 and cis-1,4 bonds of the butadiene part of SBR can be variable. For example, the vinyl content may be between 15% and 80% (mol%), the content of trans-1,4 bonds between 15% and 80% (mol%). The diene elastomer may also comprise mainly or even exclusively a polybutadiene.
    Suitable polybutadienes and in particular those having a content (mol%) in units -1.2 of between 4% and 80% or those having a content (mol%) of cis-1,4 greater than 80%, polyisoprenes, copolymers of butadiene-styrene and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) of between 0 ° C. and -70 ° C. and more particularly between -10 ° C. and -60 ° C., a styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (mol%) in -1,2 bonds of the butadiene part of between 4% and 75%, a content ( mol%) in trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C. to At -80 ° C., the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg included between at -5 ° C. and -50 ° C. In the case of butadiene-styrene-isoprene copolymers, those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40% are especially suitable. isoprene content between 15% and 60% by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content (% molar) in units -1,2 of the butadiene part of between 4% and 85%, a content (mol%) in trans-1,4 units of the butadiene part of between 6% and 80%, a content (mol% ) in units -1.2 plus -3.4 of the isoprene part of between 5% and 70% and a content (mol%) in trans units of -1.4 of the isoprenic part of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg between -5 ° C and -70 ° C.
    System for crosslinking the composition with a low modulus of ripidity
    The crosslinking system of the composition with a low modulus of rigidity may be based on sulfur and / or on sulfur and / or peroxide and / or bismaleimide donors. The crosslinking system is preferably a vulcanization system, that is to say a system based on sulfur (and / or a sulfur donor agent) and a primary vulcanization accelerator. To this basic vulcanization system are added, incorporated during the first non-productive phase and / or during the production phase as described later, various known secondary accelerators or vulcanization activators such as zinc oxide. , stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine), or known vulcanization retarders.
    The crosslinking system, preferably sulfur, may be used at a preferred level of between 0.1 and 5 phr, in particular between 0.1 and 2 phr, more preferably between 0.5 and 1.5 phr.
    Reinforcing filler of the composition with a low modulus of ripidity
    The reinforcing filler is known for its ability to strengthen a rubber composition for use in the manufacture of tires.
    According to the invention, the reinforcing filler of the composition with a low modulus of rigidity may comprise carbon black, an organic filler other than carbon black, an inorganic filler or the mixture of at least two of these fillers. Preferably, the reinforcing filler may comprise mainly, or even exclusively, carbon black. The reinforcing filler may also comprise mainly, or even exclusively, a reinforcing inorganic filler.
    Such a reinforcing filler typically consists of nanoparticles whose average size (in mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.
    The carbon black has a BET specific surface preferably of at least 90 m 2 / g, more preferably at least 100 m 2 / g. As such, blacks conventionally used in tires or their treads are suitable ( so-called pneumatic grade blacks). Among the latter, there will be mentioned more particularly the reinforcing carbon blacks of the series 100, 200, 300, or the series blacks 500, 600 or 700 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330. , N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600). The BET specific surface area of the carbon blacks is measured according to the D6556-10 standard [multipoint method (at least 5 points) - gas: nitrogen - relative pressure range Ρ / Ρ0: 0.1 to 0.3],
    As examples of organic fillers other than carbon blacks, mention may be made of functionalized polyvinyl organic fillers as described in applications WO 2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.
    "Reinforcing inorganic filler" means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called "white" filler, "clear" filler or even "non-black" filler. as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words able to replace, in its function of reinforcement, a conventional carbon black of pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
    Suitable reinforcing inorganic fillers are in particular mineral fillers of the siliceous type, preferentially silica (SiO 2). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g, especially between 60 and 300 m2 / g. As highly dispersible precipitated silicas (called "HDS"), mention may be made, for example, of the "Ultrasil" 7000 and "Ultrasil" 7005 silicas of the Degussa company, the "Zeosil" 1165MP, 1135MP and 1115MP silicas of the Rhodia company. "Hi-Sil" silica EZ150G from the company PPG, the "Zeopol" silicas 8715, 8745 and 8755 from the Huber Company, the high surface area silicas as described in the application WO 03/016387.
    In the present description, with regard to silica, the BET surface area is determined in a known manner by gas adsorption using the method of Brunauer-Emmett-Teller described in "The Journal of the American Chemical Society" Flight . 60, page 309, February 1938, more precisely according to the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: 1 hour at 160 ° C. - relative pressure range p / po: 0.05 to 0.17). The CTAB specific surface is the external surface determined according to the French standard NF T 45-007 of November 1987 (method B).
    Reinforcing inorganic fillers are also suitable for mineral fillers of the aluminous type, in particular alumina (Al 2 O 3) or aluminum (oxide) hydroxides, or reinforcing titanium oxides, for example described in US Pat. No. 6,610,261 and US Pat. No. 6,747,087. The physical state in which the reinforcing inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described above.
    In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. In particular, organosilanes or at least bifunctional polyorganosiloxanes are used.
    The content of coupling agent is advantageously less than 12 phr, it being understood that it is generally desirable to use as little as possible. Typically the level of coupling agent is from 0.5% to 15% by weight relative to the amount of inorganic filler. Its level is preferably between 0.5 and 9 phr, more preferably in a range from 3 to 9 phr. This level is easily adjusted by those skilled in the art according to the level of inorganic filler used in the composition.
    According to the invention, the level of reinforcing filler may be in a range from 10 to 160, preferably from 10 to 150 phr, preferably from 10 to 90 phr, preferably from 20 to 70 phr, preferably from 25 to 70 phr. to 60 pce.
    Advantageously, the level of reinforcing filler is in a range from 10 to 30% by volume fraction, preferably from 15 to 25% by volume, relative to the volume of the low modulus stiffness composition.
    Various additives of low stiffness modulus composition
    The low rigidity modulus composition may also comprise all or part of the usual additives usually used in elastomer compositions intended to constitute treads, for example plasticizers, fibers, pigments, protective agents such as anti-ozone waxes, anti-ozonants chemicals, anti-oxidants, anti-fatigue agents, well known to those skilled in the art.
    Advantageously, in order not to raise its extension module at 5% of deformation, the composition with low modulus of rigidity does not include a reinforcing resin and / or reinforcing fiber.
    Composition with high modulus of rigidity
    According to the invention, the tread consists of a plurality of layers comprising layers consisting of a composition with a high modulus of rigidity. The term "composition with a high modulus of rigidity" is intended to mean a composition whose extension modulus at 5% of deformation is in a range from 30 MPa to 50 GPa. Preferably, the 5% deformation modulus of the composition with high modulus of rigidity is in a range from 30 to 300 MPa, preferably from 40 to 200 MPa.
    As indicated above, a person skilled in the art can measure the rigidity of which the 5% deformation modulus according to a method based on the NF ISO 37 standard of December 2005 on a dumbbell type 2 specimen and measure the module. elasticity at 5% deformation at 23 ° C. The skilled person has many means to obtain a composition with high modulus of rigidity. For example, one skilled in the art can use high levels of reinforcing filler and / or crosslinking system and / or reinforcing fibers, for example in an elastomeric matrix. It may also, alternatively or in a complementary manner, use thermoplastic materials or thermoplastic elastomers.
    Thus, according to a first embodiment of the invention, the composition with high modulus of rigidity can be an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler, at least one crosslinking system. The high modulus stiffness composition may also be a thermoplastic or comprise a thermoplastic elastomer.
    When the composition with a high modulus of rigidity is an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler, at least one crosslinking system, the elastomeric matrix, the reinforcing filler and the crosslinking system may be identical to those of the low rigidity modulus composition. In particular: the elastomeric matrix of the composition with a high modulus of rigidity may comprise a diene elastomer, preferably an elastomer chosen from isoprenic elastomers, butadiene and styrene copolymers, polybutadienes and their mixtures, the reinforcing filler of the composition at high modulus of stiffness may comprise carbon black and / or a reinforcing inorganic filler, preferably the reinforcing filler predominantly comprises carbon black, the crosslinking system of the composition with high modulus of rigidity may comprise a crosslinking agent chosen from group consisting of sulfur, a sulfur donor, a peroxide, a bismaleimide and the mixture of at least two of these crosslinking agents.
    The level of reinforcing filler of the composition with high modulus of rigidity can generally be in a range from 10 to 160 phr, preferably from 10 to 150 phr, preferably from 10 to 90 phr, preferably from 20 to 70 phr. preferably 25 to 60 phr.
    Advantageously, the reinforcing filler content of the composition with high modulus of rigidity is in a range from 1 to 50% by volume fraction, preferably from 10 to 40%, preferably from 15 to 25% by volume fraction. , relative to the volume of the composition with high modulus of rigidity.
    If the person skilled in the art wishes to obtain an extension module with a 5% deformation greater than 30 MPa thanks to the reinforcing filler content, the level of reinforcing filler can be within a range from 25 to 50% by volume fraction, preferably from 40 to 50% of volume fraction, relative to the volume of the composition with high modulus of rigidity.
    Moreover, the crosslinking system of the composition with a high modulus of rigidity, preferably sulfur, may be used at a preferential rate of between 0.1 and 40 phr, preferably between 0.1 and 20 phr, in particular between 0.1 and 10 phr, more preferably between 0.5 and 10 phr.
    If the person skilled in the art wishes to obtain an extension module with a 5% deformation greater than 30 MPa thanks to the degree of crosslinking system, the level of crosslinking system can be between 20 and 40 phr, preferably between 30 and 40 phr. 40 pce.
    Alternatively, or in a complementary manner, according to this first embodiment of the invention, the composition with a high modulus of rigidity may comprise a reinforcing resin.
    The reinforcing resin may be for example a resin chosen from polyepoxide resins, melamine-formaldehyde resins, phenol-formaldehyde resins, urea-formaldehyde resins, polyurethane resins, unsaturated polyester resins, vinyl ester resins, polyimide resins, diallyl phthalate resins, allyl resins diglycole carbonates, polyorganosiloxane resins, preferably from the formophenolic resins or epoxy resins, the latter may in particular be used as adhesion primer.
    Preferably, the reinforcing resin may be a resin chosen from melamine-formaldehyde, phenol-formaldehyde or urea-formaldehyde resin and even more preferably the phenol-formaldehyde resin. By way of example of a commercially available resin, mention may be made, for example, of the ALNOVOL PN-320 phenol-formaldehyde resin from Allnex, 1070 Anderlecht-Brussels BELGIUM or the technol RR-110 phenol-formaldehyde resin from TECHNO WAXCHEM PVT LTD Kolkata 700046, WB, India.
    Advantageously, the reinforcing resin may contain an activator which allows the resin to crosslink. For example, the activator may be chosen from Hexamethylenetetramine (HMTA) with, for example, TECHNO WAXCHEM PVT Technic-SCH. LTD. Kolkata 700046, WB, India, or Hexa (methoxymethyl) melamine (H3M) including Cyrez CRA100 from Allnex, 1070 Anderlecht - Brussels BELGIUM.
    According to a second embodiment of the invention, the composition with a high modulus of rigidity may be a thermoplastic.
    The thermoplastic preferably has a melting or softening temperature greater than 100 ° C., preferably greater than 140 ° C. and very preferably between 170 and 300 ° C. The softening temperature can be measured, for example, according to the method described in ASTM D 1525.
    Preferably, the thermoplastic is selected from the group consisting of polyolefins, chlorinated vinyl polymers, polystyrenes, polyamides, polyesters, copolymers of ethylene and vinyl alcohol (EVOH), polyacrylates, polyacetals, and their mixtures.
    Preferably, the polyolefins are chosen from polyethylenes and polypropylenes.
    Preferably, the chlorinated vinyl polymers are chosen from polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), chlorinated polyvinyl chloride (CPVC) and mixtures thereof.
    Preferably, the polyesters are chosen from among polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC) and polyethylene naphthalate (PEN), and mixtures thereof.
    The polyamides may be chosen from aliphatic polyamides and preferably from polyamides 6, polyamides 6-6, polyamides 11 and mixtures thereof.
    An example of polyacrylate is polymethyl methacrylate (PMMA); an example of polyacetal is methylene oxide (POM).
    Thermoplastics are commercially available, sold for example for polyamides, Arkema's RAUPAN PAU, EMS-Grimory's PA12 GRILAMID, Evonik's PA6 TROGAMID, Arkema's PA12 ORGASOL. For example, they have been described, as well as their synthesis, in the documents Techniques de l'ingénieur, ref A3360 and 0702 PA polyamides, a reference from "plastic and composite materials" by B. Guérin.
    Advantageously, according to the invention, the thermoplastic may be adhered, that is to say treated to improve their adhesion to the layers comprising a composition of low rigidity modulus. For example, the thermoplastic may be adhered with a glue selected from epoxy glues followed by liquid resorcinol-formaldehyde latex (RFL) treatment and formaldehyde-based glues, preferably RFL glues. By way of example of RFL adhesive that can be used to adhere the thermoplastic, mention may be made of those described in application WO 2001/057116.
    According to a third embodiment of the invention, the composition with a high modulus of rigidity may comprise a thermoplastic elastomer (TPE).
    According to this embodiment, the composition with a high modulus of rigidity comprises at least, based on a single elastomer or elastomer by weight, a thermoplastic elastomer.
    TPEs have an intermediate structure between thermoplastic polymers and elastomers. They consist of rigid thermoplastic blocks connected by flexible elastomeric blocks, for example polybutadiene, polyisoprene, poly (ethylene / butylene) or polyisobutylene. They are often triblock elastomers with two rigid segments connected by a flexible segment. The rigid and flexible segments can be arranged linearly, star or connected. Typically, each of these segments or blocks contains at least more than 5, usually more than 10 base units (eg, styrene units and isoprene units for a styrene / isoprene / styrene triblock copolymer). The thermoplastic elastomer may be chosen from the group consisting of thermoplastic styrene elastomers (TPS), ether-amide block copolymers (PEBA), copolyesters (COPE), thermoplastic polyurethane elastomers (TPU), vulcanized thermoplastics (TPV) thermoplastic polyolefins (TPO) and the mixture of these TPEs. Advantageously, the thermoplastic elastomer is a TPS elastomer. By way of example of TPS elastomer, mention may be made of the following copolymers: Styrene-Butadiene-Styrene (SBS), Styrene-Isoprene-Styrene (SIS), Styrene-ethylene / Butylene-Styrene (SEBS), Styrene-Isoprene / Butylene Styrene (SIBS), Styrene-ethylene / propylene-Styrene (SEPS) and ii) less than 90% by weight, preferably 0% to 80%, of one or more styrene-butadiene di-block copolymers (SB) or Styrene-lsoprene (SI) or Styrene-ethylene / butylene (SEB) or Styrene-lsoprene / butylene (SIB) or Styrene-ethylene / propylene (SEP).
    It is preferred that the glass transition temperature (Tg, measured according to ASTM D3418) of the elastomeric block of the TPE elastomer is less than -20 ° C., more preferentially less than -40 ° C.
    The number-average molecular weight (denoted Mn) of the TPE elastomer is preferably between 30,000 and 500,000 g / mol, more preferably between 40,000 and 400,000 g / mol. The number-average molecular weight (Mn) of the TPS elastomer is determined in known manner by steric exclusion chromatography (SEC). The sample is solubilized beforehand in tetrahydrofuran at a concentration of approximately 1 g / l; then the solution is filtered through a 0.45 μm porosity filter before injection. The apparatus used is a "WATERS alliance" chromatographic chain. The elution solvent is tetrahydrofuran, the flow rate 0.7 ml / min, the system temperature 35 ° C and the analysis time 90 min. A set of four WATERS columns in series, of trade names "STYRAGEL" ("HMW7", "HMW6E" and two "HT6E") is used. The injected volume of the solution of the polymer sample is 100 μΙ. The detector is a "WATERS 2410" differential refractometer and its associated software for the exploitation of chromatographic data is the "WATERS MILLENIUM" system. The calculated average molar masses relate to a calibration curve made with polystyrene standards. The polydispersity index Ip (booster: Ip = Mw / Mn with Mw weight average molecular weight) of the TPS elastomer is preferably less than 3; more preferably Ip is less than 2.
    According to the third embodiment of the present invention, the TPE elastomer may be the only elastomer composition with high modulus of rigidity or be associated with other elastomers.
    If any other elastomers are used in the high modulus stiffness composition, the TPE elastomer constitutes the majority elastomer by weight. Such complementary elastomers, minority by weight, could be, for example, diene elastomers such as natural rubber or synthetic polyisoprene, butyl rubber or thermoplastic elastomers other than styrenic, within the limit of the compatibility of their microstructures. Preferably, the elastomer other than the thermoplastic elastomer is chosen from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
    Thus, the composition with a high stiffness modulus may comprise from 50 to less than 100 phr, preferably from 70 to less than 100 phr, preferably from 80 to less than 100 phr, preferably from 90 to less than 100 phr. TPE. In this case, the composition with a high modulus of rigidity comprises from more than 0 to 50 phr, preferably from more than 0 to 30 phr, preferably from more than 0 to 20 phr, preferably from 0 to 10 phr of a composition. another elastomer different from TPE.
    However, according to one particular embodiment, the thermoplastic elastomer is the only thermoplastic elastomer, advantageously the only elastomer, present in the composition with a high modulus of rigidity. In other words, advantageously, the composition with high modulus of rigidity comprises exclusively, that is to say 100 phr, of TPE.
    The TPE elastomers can be used conventionally, by extrusion or molding, for example from a raw material available in the form of beads or granules.
    TPE elastomers are commercially available, sold for example as regards SIBS by KANEKA under the name "SIBSTAR" (e.g. "Sibstar 102T", "Sibstar 103T" or "Sibstar 073T"). For example, they have been described, as well as their synthesis, in patent documents EP 731112, US Pat. No. 4,946,899 and US Pat. No. 5,260,383. They were first developed for biomedical applications then described in various specific applications of TPE, in particular to TPS elastomers, as varied as medical equipment, parts for automobiles or household appliances, sleeves for electrical wires, sealing pieces or elastics (see for example EP 1 431 343, EP 1 561 783, EP 1 566 405, WO 2005 / 103146).
    According to this third embodiment of the present invention, the high modulus stiffness composition may comprise a reinforcing filler and a crosslinking system. Preferably, the reinforcing filler and / or the crosslinking system of the high stiffness modulus composition according to the third embodiment are identical to those of the first embodiment of the present invention.
    Sculpture of the tread
    The tread according to the present invention comprises a tread.
    According to the invention, the sculpture of the tread consists of a plurality of parallel and adjacent layers, the layers being oriented in the sculpture parallel to a plane which is (i) perpendicular to the equatorial plane and (ii) oriented at an angle expressed in degrees to the radial plane, the angle a being defined by the formula a = 45 +/- x, where x is within a range of 10 to 30. In other words, the layers are oriented in the sculpture parallel to a plane which is (i) perpendicular to the equatorial plane and (ii) oriented at an angle α expressed in degrees relative to the radial plane, the angle a being within a range from at 35 degrees or 55 to 75 degrees.
    Unless otherwise indicated, the orientation of the layers in the tread according to the invention is expressed with respect to a tread disposed on a tire. Those skilled in the art will easily convert the orientation of the layers when the tread is laid flat, for example in the form of a semi-finished. Assuming that the tread is flat, it could be defined in directions parallel to its length, width and thickness which correspond respectively to the circumferential directions "X", transverse "Y" and radial "Z" . The circumferential plane would then be a plane defined by the length and thickness of the tread, the radial plane would be a plane defined by the width and thickness of the tread. Those skilled in the art can measure the angle of the layers within the tread by removing a portion of the tread, preferably by removing half the width of a rib in a plane parallel to the XoZ plane, of in order to reveal an interface containing the layers, and by taking a test piece material by cutting the tread according to Figure 2 and establishing the orientation histogram of the layers in the plane XOZ with respect to the direction Z by optical microscopy in reflection.
    According to the invention, the layers can be oriented to the sculpture parallel to a plane which is (i) perpendicular to the equatorial plane and (ii) oriented at an angle α expressed in degrees with respect to the radial plane, the angle a being defined by the formula a = 45 +/- x, where x is within a range of 12.5 to 27.5 (i.e. 17.5 to 35.5 degrees or 57.5 to 72 , 5 degrees), preferably 15 to 25 (i.e., 20 to 30 degrees or 60 to 70 degrees), preferably x is 20 (i.e., 25 degrees). or 65 degrees). Unless otherwise indicated, the angle a is expressed in absolute value. Those skilled in the art understand that when speaking of layers oriented at the same angle α, they may be layers having substantially the same angel a, that is to say that the layers are oriented according to a angle a with a small standard deviation, for example a standard deviation of 3 degrees or less, over at least 80% of the XoZ plane surface.
    Whatever the value of the angle α in the range a = 45 +/- 10 to 30 degrees, this orientation gives the composite material the ability to transfer a portion of the component Fz from the forces of the ground on the tire to the ground. Fx component, that is to say, from the vertical component to the horizontal component in the direction of rolling of the tire. This coupling ratio is particularly advantageous for improving the wear resistance of tires for civil engineering vehicles, especially in their specific conditions of use.
    Depending on the angle of the layers within the sculpture, the coupling rate is not the same. Thus, when the angle a is between 15 and 35 degrees (i.e., a = 45 - from 10 to 30), the sculpture will transform the component Fz into a positive Fx component. It can be noted that the closer the angle a is to 25 degrees, the higher the coupling rate is. This embodiment is particularly advantageous for improving the wear resistance of tires of vehicles carrying heavy loads uphill.
    On the other hand, when the angle a is between 55 and 75 degrees (that is, a = 45 + from 10 to 30), the sculpture will transform the component Fz into a negative Fx component. The closer the angle is to 65 degrees, the higher the coupling rate. This embodiment is particularly advantageous for improving the wear resistance of tires of vehicles traveling downhill empty.
    When the angle a is between 35 and 55 degrees, the coupling ratio becomes too low, or even zero around 45 degrees, to give the desired property to the sculpture of the tread according to the invention. The same is true when the angle a is less than 15 degrees or greater than 75 degrees.
    According to the invention, the plurality of layers comprises layers consisting of a composition with a low modulus of rigidity and layers consisting of a composition with a high modulus of rigidity.
    More particularly, the plurality of layers comprises at least one (i.e., one or more) group of layers consisting of a low modulus stiffness composition and at least one (i.e. one or more ) group layers consisting of a composition with high modulus of rigidity.
    In the present, the term "a group of layers", one or more layers identical to each other. In other words, when the plurality of layers comprises several groups of different layers, these layers may differ from each other by the nature of the elastomeric matrix, the thermoplastic or the thermoplastic elastomer, the nature or the concentration in charge reinforcing, nature or concentration of reinforcing resin, crosslinking system, additives, etc.
    Thus, the plurality of layers is constituted by at least two groups of different layers, or even more, for example three, four or five groups of different layers from each other. Advantageously, the plurality of layers consists of two groups of different layers, that is to say by a group of layers consisting of a low stiffness modulus composition and a group of layers consisting of a high modulus stiffness composition. , preferably arranged alternately.
    Any distribution of layers consisting of a low rigidity modulus composition and layers consisting of a high modulus stiffness composition can be implemented. For example, the layers can be distributed alternately or not. For example, when the plurality of layers comprises two groups of different layers (for example called A and B respectively), the distribution can follow the following formula: ((AWBW), in which: "nA" and "nB" represent independently the an integer chosen from 1 to 10, preferably from 1 to 5, preferably from 1 to 2, preferably 1.
    When the composite material comprises more than two groups of different layers (for example called A, B, ..., X respectively), the distribution may follow the following formula: ((A) nA (B) nB (...) n ... (X) nx), wherein: "nA", "nB", "n" and "nX" independently of one another represent an integer selected from 1 to 10, preferably from 1 to 5, preferably from 1 to 2, preferably 1.
    The total number of layers within the sculpture is limited by the length of the tread. The skilled person is able to determine this number according to the thickness of the layers and their orientation within the sculpture.
    Preferably, according to the invention, the sculpture of the tread consists of a group of layers consisting of a composition with a low modulus of rigidity and a group of layers consisting of a composition with high stiffness modulus distributed alternately within tread sculpture (Figure 2).
    Advantageously, the low stiffness modulus composition has an extension stiffness which is at least 5 times less, preferably at least 10 times less, than that of the high stiffness modulus composition. Those skilled in the art are able to determine how stiffness is measured by the extension of low and high rigidity modulus compositions. For example, he can use a method based on the NF ISO 37 standard of December 2005 on a dumbbell type 2 specimen and measure the modulus of elasticity at 5% deformation at 23 ° C.
    Advantageously, the modulus EH, and the volume fraction φΗ of the high modulus composition and the modulus EB and the volume fraction φΒ (or 1 - φΗ) of the low modulus composition are defined in such a way that the formula
    is less than 0.67, preferably between 0.01 and 0.5. The thickness of each of the layers consisting of a composition with a low modulus of rigidity may be in a range from 1 to 20 mm, preferably from 1 to 10 mm. The thickness of each of the layers constituted by a high modulus of rigidity composition can be in a range from 0.1 to 20 mm, preferably from 0.1 to 10 mm. Preferably, when the composition with a high modulus of rigidity is a thermoplastic, the thickness of each of the layers may be in a range from 0.1 to 5 mm, preferably from 0.1 to 2 mm. When the composition with a high modulus of rigidity comprises an elastomeric matrix, or even a thermoplastic elastomer, the thickness of each of the layers may be in a range from 0.1 to 20 mm, preferably from 0.1 to 10 mm.
    Advantageously, the layer volume of the low modulus stiffness composition can be from 50 to 95% by volume, preferably from 60 to 95% by volume, based on the tread volume of the tread. Thus, the volume of layers of the composition with high modulus of rigidity can respectively represent from 5 to 50% by volume, preferably from 5 to 40% by volume, relative to the volume of the sculpture of the tread.
    pneumatic
    The present invention can be applied to any type of tire. Thus, the present invention also relates to a tire comprising a tread according to the invention.
    Generally speaking, a tire comprises a tread intended to come into contact with the ground via a rolling surface and connected via two sidewalls to two beads intended to provide a mechanical connection. between the tire and the rim on which it is mounted.
    A radial tire more particularly comprises a reinforcing reinforcement, comprising a crown reinforcement, radially inner to the tread, and a carcass reinforcement, radially inner to the crown reinforcement.
    A tire may be provided with a carcass reinforcement surmounted radially on the outside by a crown reinforcement in order to make a hooping of said carcass reinforcement. The crown reinforcement is generally formed by a stack of a plurality of reinforcing plies, these reinforcements making generally no harm to the circumferential direction.
    A tire includes a tread whose tread surface is provided with a tread formed by a plurality of grooves delimiting relief elements (blocks, ribs) so as to generate material edges and troughs. These grooves represent a void volume which, relative to the total tread volume (including both the volume of relief elements and that of all grooves) is expressed as a percentage herein referred to as "rate". of hollow volume ". A trough volume of zero indicates a tread without grooves or recesses.
    The present invention is particularly well suited to tires for civil engineering vehicles and heavy goods vehicles, more particularly for civil engineering vehicles whose tires are subject to very specific constraints. Thus, advantageously, the tire according to the invention is a tire for civil engineering vehicles or heavy goods vehicles, preferably civil engineering vehicles.
    The tread according to the invention may have one or more grooves with an average depth of 15 to 120 mm, preferably 65 to 120 mm.
    The tires according to the invention may have a diameter of from 20 to 63 inches, preferably from 35 to 63 inches.
    Furthermore, the average rate of trough on the entire tread according to the invention can be in a range from 5 to 40%, preferably from 5 to 25%.
    Preparation of the low modulus stiffness composition
    The sculptures of the tread can be obtained according to the method defined below.
    Masterbatchs (mixtures containing all the ingredients with the exception of the crosslinking system) can be manufactured in appropriate mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first phase of work or thermomechanical mixing (sometimes referred to as a "non-productive" phase) at a high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C, followed by a second phase of mechanical work (sometimes called a "productive" phase) at a lower temperature, typically less than 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which the agent is incorporated chemical crosslinking, in particular the crosslinking system. As an example for obtaining masterbatchs, the first (non-productive) phase is conducted in a single thermomechanical step during which all the necessary constituents are introduced into a suitable mixer such as a conventional internal mixer. , any additional coating or processing agents and other various additives, with the exception of the vulcanization system. The total mixing time, in this non-productive phase, is preferably between 2 and 10 min. After cooling the mixture thus obtained during the first non-productive phase, the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 min.
    The sculpture composition thus obtained is then calendered, for example in the form of a layer.
    Preparation of the composition with high modulus of rigidity
    When the composition with high modulus of rigidity is an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler, at least one crosslinking system, or when it comprises a thermoplastic elastomer, this composition may be prepared according to a method similar or identical to that of the composition with low modulus of rigidity.
    When the high modulus stiffness composition is a thermoplastic, it can be manufactured in suitable mixers, according to methods well known to those skilled in the art. For example, in a first step, the thermoplastic material, generally in the form of a granule, is introduced into a mixer and is worked or kneaded at a temperature above its softening point, generally at a temperature above 10 ° C. melting or the glass transition temperature of the thermoplastic.
    In a second step the thermoplastic material is cooled to a temperature below its softening point and extruded or calendered in the form of a sheet or plate which is then cut so as to obtain centimetric elements of desired shapes and dimensions.
    Preparation of the tread
    To obtain the desired orientation of the layers in the tread according to the present invention, any technique that is well known to a person skilled in the art, in particular the method described in application WO 2008/027045, may be used. For example, low and high modulus stiffness composition layers may be alternately flattened and cut by any suitable means, for example by waterjet cutting, at the desired angle, so as to form elements of sculptures. may be arranged on a tire raw tire in a manner well known to those skilled in the art. Other advantages may still appear to those skilled in the art on reading the examples below, illustrated by the accompanying figures, given for illustrative and non-limiting.
    Brief description of the figures
    FIG. 1 is a diagrammatic representation of a tire (1) whose rolling race comprises a rib (2) situated in the central zone of the tire (1), blocks (3), the rib and the blocks being separated. by circumferential grooves (4) and substantially transverse grooves (5).
    Figure 2 is a schematic representation of several embodiments of a sculpture according to the invention, in section along the XZ plane. This sculpture is composed of a plurality of layers (cl) consisting of a composition with a high modulus of rigidity (finer) and layers (c2) consisting of a composition with a low rigidity modulus (thicker), parallel, adjacent to each other, and oriented parallel to a plane which is (i) perpendicular to the XZ plane and (ii) oriented at an angle (a) of 20 degrees for E1 and E3, of 25 degrees for E4 and 30 degrees for E2, compared to the YZ plane.
    EXAMPLES A) Samples with a surface area of 10 cm x 10 cm and a thickness of 3 cm were produced according to the method described in application WO 2008/027045 with layers consisting of compositions with low and high modulus of rigidity arranged alternately.
    We define below: "X": a direction parallel to the direction of stress of the sample, itself parallel to the length of the sample. "Y": a direction parallel to the width of the sample. "Z": a direction parallel to the thickness of the sample.
    A composition A which is a low stiffness modulus composition and a composition B which is a high stiffness modulus composition have been prepared. These compositions and the associated experimental results are presented in Table 1 below:
    Table 1
    (1) Natural rubber (2) "Ultrasil VN3" sold by Evonik (3) N234 grade carbon black according to ASTM D-1765 (4) N330 grade carbon black according to ASTM D-1765 (5) Umicore industrial grade zinc oxide (6) Mn 6000-20000 g / mol polyethylene glycol marketed by Sasol Mari (7) Phenol-formaldehyde resin (8) Hexamethylenetetramine hardener (9) Hexa hardener (methoxymethyl) melamine (10) N-cyclohexyl-2-benzothiazol sulfenamide, "Santocure CBS", marketed by Flexsys
    (11) N-tert-butyl-2-benzothiazyl sulfenamide sold under the name TBBS (12) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine sold under the name 6PPD (a) Modulus of elasticity at 5% deformation
    Samples E1, E2, E3 and E4 were made from compositions A and B in the form of layers arranged alternately and parallel to a plane defined by (i) the Y direction and (ii) a line oriented at 20, 25 or 30 degrees to Z direction in a plane defined by the X and Z directions.
    An RI control sample was made with Composition A only, without using oriented layers.
    Measurements of the mechanical properties were carried out after baking the aforementioned compositions at a temperature of 150 ° C. for 30 minutes. The results were obtained from dumbbell type 2 test specimens at 5% deformation at 23 ° C. according to the NF ISO 37 standard of December 2005.
    To analyze the transfer of the forces of the soil on the specimen of the vertical component (Fz) towards the horizontal component in the running direction (Fx) (the coupling ratio), a force Fz of 900daN corresponding to a pressure was applied. average of 9 bar or 600daN corresponding to an average pressure of 6 bar on the surface of the samples using an electric cylinder and the resulting force Fx was measured using a force sensor. The Fx ratio divided by Fz is called the coupling ratio and is measured at two different average pressures.
    Samples RI, E1, E2, E3 and E4 and the associated experimental results are shown in Table 2 below:
    Table 2
    * not applicable
    These results show that the samples according to the present invention (comprising low and high modulus stiffness composition layers) create a coupling ratio with respect to a sample comprising only a low modulus stiffness composition. Samples which comprise a composition volume B of 20% (E1 and E2) have been found to have a higher coupling ratio than samples comprising a composition B volume of 11% (E3 and E4). B) A similar experiment was carried out using, in place of the aforementioned composition B, a composition C (high modulus of rigidity) of a thermoplastic material, namely a polyamide 66 adhered with an RFL glue. The layers of composition A were 2 mm thick and that of the composition C, 1 mm thick. The volume fraction of the composition C was therefore 33% relative to the volume of the test piece.
    For this experiment, the layers of compositions A and C were arranged alternately and oriented parallel to a plane defined by (i) the Y direction and (ii) a line oriented at 25 or 45 degrees with respect to Z direction in a defined plane by the X and Z directions.
    The observed results have demonstrated that no coupling rate is observed when the angle of the layers is 45 degrees, while a positive coupling rate is obtained when the angle of the layers is 25 degrees.
    The various measurements performed by the Applicants have demonstrated that the coupling ratio obtained was sufficient for the implementation of the present invention when the layers are oriented at an angle of 15 to 35 degrees or 55 to 75 degrees.
    The present invention therefore provides treads for transferring a proportion of the ground forces on the tire of the component Fz into different components Fx, to effectively improve the wear resistance of the tires. These results are particularly interesting for vehicles traveling on non-bituminous soils, such as most civil engineering vehicles and some heavy goods vehicles.
    权利要求:
    Claims (29)
    [1" id="c-fr-0001]
    A tread comprising at least one tread made up of a plurality of parallel and adjacent layers, the layers being oriented in the tread parallel to a plane which is (i) perpendicular to the equatorial plane and (ii) oriented to a angle expressed in degrees relative to the radial plane, the angle a being defined by the formula a = 45 +/- x, where x is within a range of 10 to 30, the plurality of layers comprising layers consisting of a composition with a low modulus of rigidity, the expansion modulus at 5% of deformation is in a range from 2 to 8 MPa and layers consist of a high modulus stiffness composition whose expansion module at 5% deformation in a range from 30 MPa to 50 GPa.
    [2" id="c-fr-0002]
    2. A tread according to claim 1, wherein the low stiffness modulus composition is an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler and at least one crosslinking system.
    [3" id="c-fr-0003]
    3. A tread according to claim 2, wherein the elastomeric matrix of the low rigidity modulus composition comprises a diene elastomer, preferably an elastomer selected from isoprenic elastomers, butadiene and styrenic copolymers, polybutadienes and mixtures thereof.
    [4" id="c-fr-0004]
    4. A tread according to claim 2 or 3, wherein the reinforcing filler of the low stiffness modulus composition is selected from carbon black and / or inorganic filler.
    [5" id="c-fr-0005]
    The tread of any one of claims 2 to 4, wherein the low rigidity modulus composition crosslinking system comprises a crosslinking agent selected from the group consisting of sulfur, a sulfur donor, a peroxide, a bismaleimide and the mixture of at least two of these crosslinking agents.
    [6" id="c-fr-0006]
    A tread according to any one of claims 2 to 5, wherein the low rigidity modulus composition does not comprise a reinforcing resin.
    [7" id="c-fr-0007]
    A tread according to any one of claims 2 to 6, wherein the reinforcing filler of the low rigidity modulus composition is present in the low stiffness modulus composition at a concentration of from 10 to 160 parts by weight per hundred parts of elastomer, preferably from 10 to 90 phr.
    [8" id="c-fr-0008]
    8. Tread according to any one of claims 2 to 7, wherein the crosslinking system of the low stiffness modulus composition is present in the composition at low modulus of rigidity at a concentration ranging from 0.1 to 5 phr preferably from 0.1 to 2 phr.
    [9" id="c-fr-0009]
    9. A tread according to any one of claims 1 to 8 wherein the composition with high modulus of rigidity is an elastomeric composition based on an elastomeric matrix, at least one reinforcing filler and at least one crosslinking system.
    [10" id="c-fr-0010]
    10. A tread according to claim 9, wherein the elastomeric matrix of the high modulus stiffness composition comprises a diene elastomer, preferably an elastomer selected from isoprenic elastomers, butadiene and styrenic copolymers, polybutadienes and mixtures thereof.
    [11" id="c-fr-0011]
    11. A tread according to claim 9 or 10, wherein the reinforcing filler of the composition with high modulus of rigidity mainly comprises carbon black.
    [12" id="c-fr-0012]
    A tread according to any one of claims 9 to 11, wherein the crosslinking system of the high stiffness modulus composition comprises a crosslinking agent selected from the group consisting of sulfur, a sulfur donor, a peroxide, a bismaleimide and the mixture of at least two of these crosslinking agents.
    [13" id="c-fr-0013]
    13. Tread according to any one of claims 9 to 12, composition with high modulus of rigidity comprises at least one reinforcing resin.
    [14" id="c-fr-0014]
    14. A tread according to claim 13, wherein the reinforcing resin of the composition with high modulus of rigidity is chosen from polyepoxide resins, melamine-formaldehyde resins, phenol-formaldehyde resins, urea-formaldehyde resins, polyurethane resins, polyester resins. unsaturated resins, vinyl ester resins, polyimide resins, diallyl phthalate resins, allyl diglycole carbonates resins, polyorganosiloxane resins.
    [15" id="c-fr-0015]
    15. A tread according to any one of claims 9 to 14, wherein the reinforcing filler of the composition with high modulus of rigidity is present in the composition with high modulus of rigidity at a concentration ranging from 10 to 160 phr, preferably from 10 to 90 phr.
    [16" id="c-fr-0016]
    16. Tread according to any one of claims 9 to 15, wherein the crosslinking system of the composition with high stiffness modulus is present in the high modulus stiffness composition at a concentration ranging from 0.1 to 40 preferably from 0.5 to 10 phr.
    [17" id="c-fr-0017]
    A tread according to any one of claims 1 to 8, wherein the high modulus stiffness composition is a thermoplastic or comprises a thermoplastic elastomer.
    [18" id="c-fr-0018]
    18. Tread according to claim 17, wherein the thermoplastic is selected from polyolefins, chlorinated vinyl polymers, polystyrenes, polyamides, polyesters, copolymers of ethylene and vinyl alcohol, polyacrylates, polyacetals. and their mixtures.
    [19" id="c-fr-0019]
    19. A tread according to claim 17 or 18, wherein the thermoplastic is adhered, preferably with a resorcinol-formaldehyde latex glue.
    [20" id="c-fr-0020]
    20. A tread according to claim 17, wherein the thermoplastic elastomer is selected from thermoplastic styrene elastomers, ether-amide block copolymers, copolyesters, thermoplastic polyurethane elastomers, vulcanized thermoplastics, thermoplastic polyolefins and mixtures thereof.
    [21" id="c-fr-0021]
    21. Tread according to any one of claims 1 to 20, wherein the EH module, and the volume fraction φΗ of the high modulus composition and the EB module and the volume fraction φΒ (or 1 - φΗ) of the low-modulus composition are defined so that the formula

    less than 0.67.
    [22" id="c-fr-0022]
    22. A tread according to any of claims 1 to 21, wherein the 5% deformation modulus of the low stiffness modulus composition is within a range of 3 to 6 MPa.
    [23" id="c-fr-0023]
    23. Tread according to any one of claims 1 to 22, wherein the 5% deformation modulus of the high stiffness modulus composition is within a range of 30 to 300 MPa, preferably from 40 to 200 MPa.
    [24" id="c-fr-0024]
    A tread according to any one of claims 1 to 23, wherein the volume of the layers of the low modulus stiffness composition is from 50 to 95% by volume of the tread pattern.
    [25" id="c-fr-0025]
    25. A tread according to any one of claims 1 to 24 wherein the layers of the low modulus stiffness composition have a thickness in a range of 1 to 20 mm, preferably 1 to 10 mm.
    [26" id="c-fr-0026]
    26. Tread according to any one of claims 1 to 25, wherein the layers of the composition with high modulus of rigidity have a thickness in a range from 0.1 to 20 mm, preferably 0.1 at 10 mm.
    [27" id="c-fr-0027]
    A tread according to any one of claims 1 to 26, wherein the layers of the low rigidity modulus composition and the high stiffness modulus composition are alternately arranged.
    [28" id="c-fr-0028]
    28. A tire comprising a tread as defined in any one of claims 1 to 27.
    [29" id="c-fr-0029]
    29. A tire according to claim 28, said tire being a civil engineering tire.
    类似技术:
    公开号 | 公开日 | 专利标题
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    同族专利:
    公开号 | 公开日
    US20180370288A1|2018-12-27|
    CN108472998A|2018-08-31|
    FR3045495B1|2018-01-05|
    WO2017109339A1|2017-06-29|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP0105822A2|1982-06-09|1984-04-18|The Goodyear Tire & Rubber Company|Tread|
    EP1630003A1|2004-08-26|2006-03-01|Sumtiomo Rubber Industries Ltd|Heavy-duty pneumatic tire|
    JP2756564B2|1988-09-07|1998-05-25|東洋ゴム工業株式会社|Pneumatic tire|
    JPH02162104A|1988-12-14|1990-06-21|Yokohama Rubber Co Ltd:The|Pneumatic tire|
    JPH0325003A|1989-06-23|1991-02-01|Toyo Tire & Rubber Co Ltd|Low profile tire|
    JPH0687302A|1992-09-07|1994-03-29|Bridgestone Corp|Heavy load radial tire for construction vehicle|
    EP0761479A3|1995-07-24|1997-06-04|Goodyear Tire & Rubber|Aligning torque generation via inclined lateral tread grooves|
    US6058994A|1997-05-19|2000-05-09|The Yokohama Rubber Co., Ltd.|Rubber composition for tire-tread having high frictional force on ice and pneumatic tire using same|
    JP2006168564A|2004-12-16|2006-06-29|Bridgestone Corp|Pneumatic tire|
    FR2930194B1|2008-04-16|2010-04-09|Michelin Soc Tech|PNEUMATIC TIRE COMPRISING A RUBBER MIXTURE LAYER WITH A VERY HIGH MODULE.|
    JP2009255747A|2008-04-16|2009-11-05|Bridgestone Corp|Pneumatic tire|
    CA2857940C|2011-12-16|2017-02-28|Compagnie Generale Des Etablissements Michelin|Tread for pneumatic tyre|
    JP5992787B2|2012-02-15|2016-09-14|東洋ゴム工業株式会社|Pneumatic tire|
    FR2992897B1|2012-07-05|2014-08-15|Michelin & Cie|PNEUMATIC COMPRISING A TREAD TAPE CONSISTING OF SEVERAL ELASTOMERIC MIXTURES|
    CN104870216B|2012-12-28|2017-04-05|米其林企业总公司|Air tread and the pneumatic tire with the tyre surface|
    JP2014231267A|2013-05-28|2014-12-11|住友ゴム工業株式会社|Tire for two-wheeled vehicle|
    JP2016523758A|2013-06-10|2016-08-12|カンパニー ジェネラレ デ エスタブリシュメンツ ミシュラン|Tires with improved tread|
    FR3007693B1|2013-07-01|2015-07-17|Michelin & Cie|PNEUMATIC COMPRISING AN IMPROVED BEARING BAND|
    KR102085096B1|2013-07-30|2020-03-05|삼성전자주식회사|Operating method for nonvolatile memory device and operating method for memory controller controlling nonvolatile memory device|
    KR20150056000A|2013-11-14|2015-05-22|주식회사 만도|Adaptive cruise control apparatus of vehicle with sensing distance regulation function and method for thereof|
    CN105346334A|2015-11-10|2016-02-24|青岛双星轮胎工业有限公司|Industrial radial tire|WO2020113002A1|2018-11-30|2020-06-04|Moyle Nichole|Material with enhanced sliding friction|
    US11104125B2|2019-03-19|2021-08-31|Ricoh Company, Ltd.|Liquid discharge apparatus|
    JP2020196842A|2019-06-05|2020-12-10|住友ゴム工業株式会社|Pneumatic tire|
    法律状态:
    2016-12-22| PLFP| Fee payment|Year of fee payment: 2 |
    2017-06-23| PLSC| Search report ready|Effective date: 20170623 |
    2017-12-21| PLFP| Fee payment|Year of fee payment: 3 |
    2019-09-27| ST| Notification of lapse|Effective date: 20190906 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1563041A|FR3045495B1|2015-12-22|2015-12-22|COMPOSITE MATERIALS BASED ON STACKING ORIENTED WITH HARD-MIX MIXTURES FOR MECHANICAL COUPLING|FR1563041A| FR3045495B1|2015-12-22|2015-12-22|COMPOSITE MATERIALS BASED ON STACKING ORIENTED WITH HARD-MIX MIXTURES FOR MECHANICAL COUPLING|
    PCT/FR2016/053460| WO2017109339A1|2015-12-22|2016-12-15|Composite materials consisting of an oriented stacking of hard-soft mixtures for mechanical coupling in the production of tyre treads|
    US16/065,346| US20180370288A1|2015-12-22|2016-12-15|Composite materials consisting of an oriented stacking of hard-soft mixtures for mechanical coupling in the production of tire treads|
    CN201680074958.2A| CN108472998A|2015-12-22|2016-12-15|The composite material of mechanical couplings being made of hard-soft mixture of oriented stack is used in the preparation of tire tread|
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